Preparation of succinonitrile



duce thef' 'corresponding cyanoethyl derivativ 'acrylonit'rile and a ketone cyanohydrin would a Patented Apr. 3, 1951 UNITED STATES PATENT OFFICER"? PREPARATION oi SUCCINONITRILE Charles E. Brockway, v.likron, Ohio, assignor to The B. F. Goodrich Company, New York, N. Y., a corporation of N ew, ,York

No Drawing. Application December 2, 1949,

Serial No. 130,866

5 Claims. (Cl. 260-4653) This invention relates to the preparation of i snccinonitrile and more specifically pertains to; I

the preparation of succinonitrile by reacting acrylonitrile (vinyl cyanide) with a ketone cy' anohydrin. ncrylonitrile is a well known cyanoethylating agent reacting with the active hydrogen of-aii OH roup of many organic compounds to pro- For example, aldehyde cyanohydrins such glyconitrilej and lactonitrile react with acryltlnitrile to form cyanoethyl derivatives. Accord ingly, it was to be expected that reaction between result infi'cyanoethylation of the 'hydroxyl grou 1 according' to the following'equation:

where R1 and R2 are hydrocarbon radicals.

I have ,discovered, however, that ketone cyanohydrinszjreact with acrylonitrile in the presence of a basic material as catalyst to form succincnitrile rather than-the expected cyanoethyl 'derivatives. The reaction to form the succinonitrile proceedsas iollows: :5; "R1 N R11) ON on o 4 om=cHoN (Beets.

where R and R2 are hydrocarbon radicals As this la erequation indicates the ketone from- I. starting cyanohydrin. is .derivQe "is 1: 3, by-product of the reaction. "Cori 'hydrin'forfurther use as a reactant.

material which is employed as cata process of this invention is not critical 1e either inorganic or organic. Espe cially s itable are tertiary amines such trimethyfa mine, triethyl amine, tributyl amiria tif'icy'clohexyl amine, tribenzyl amine, hexamethylene tetramine, pyridine, triethanol amine and thelike ammonium hydroxide and quaternary ainmon m bases such as'trimethyl benz'yl' momuinghydroxide and the like alkali and 'alka 2 line earth metal hydroxides such as sodium potassium and calcium hydroxides and salts of strong bases with weak acids such as sodium or potassium carbonates, cyanides, acetates, propionates, benzoates, etc. However, other basic materials including primary and secondary amines such as ethyl amine, dimethyl-amine, ethylene diamine, diethylene triamine, cyclohexyl amine, benzyl amine, ethanol amine, aniline, etc are also suitable, it being understood thatbasic materials in general are operative. The amount ofbasic catalyst used is likewise not a critical factor and may be varied considerably with the material used but in general from 0.5 to 5% of catalyst based on the total weight of the reactants is employed.

As indicated by the last written equation above any desired ketone cyanohydrin can be employed.- However, since the ketone residue of the cyanohydrin is recovered during the reaction and since aromatic ketones such as acetophenone, benzophenone and the like are high boiling liquid or solid materials which are rather difficultly separated from the succinonitrile, it is preferred that the ketone cyanohydrin employed be an aliphatic or alicyclic ketone cyanohydrin. Best results are obtained when using ketone eyanohydrins of the structure -R.1- ON.

DHTL i drum-ethyl butylketcrieifcyanohydr'in, ethyl 'iso 2,547,686 l a r.- 'j.

butyl ketone cyanohydrin, ethyl amyl ketone cyanohydrin, ethyl isoamyl ketone cyanohydrin, ethyl hexyl ketone cyanohydrin, dipropyl ketone cyanohydrin, diisopropyl ketone cyanohydrin, propyl isopropyl ketone cyanohydrin, propyl butyl ketone cyanohydrin, isopropyl butyl ketone cyanohydrin, propyl isobutyl ketone cyanohydrin, isopropyl isobutyl ketone cyanohydrin, propyl amyl ketone cyanohydrin, isopropyl amyl ketone cyanohydrin, propyl hexyl ketone cyanohydrin, isopropyl hexyl ketone cyanohydrin, the butyl amyl ketone cyanohydrins, the butyl hexyl ketone cyanohydrins the diamyl ketone cyanohydrins, the amyl hexyl ketone cyanohydrins, the dihexyl ketone cyanohydrins, dicyclopentyl ketone cyanohydrin, dicyclobutyl ketonecyanohydrin, dicyclohexyl ketone cyanohydrim' methyl cyclopropyl ketone cyanohydrin, methyl cy'clopentyl ketone cyanohydrin, methyl cyclohexylketone cyanohydrin, ethyl isopropyl ketone cyanohy-' drin, propyl cyclohexyl ketone .cyanohyldrin iso propyl cyclohexyl ketone cyanohydrin, butylcyclohexyl ketone cyanohydrin, isobutyl cyclohexyl ketone cyanohydrin, amyl cyclohexyl ketone'cyanohydrin, n-hexyl cyclohexyl ketone cyanohydr-in, cyclobutanone cyanohydrin, :cyclopentanone cyanohydr-in and cyclohexanone cyanohydrin.

The process of forming succinonitrile is readily and. conveniently carried out by combining acrylonitrile and the' ketone cyanohydrin in any desired' propo'rtions butpre'ferably in substantially equimolecular proportions, adding a basic catalyst, heating the-resulting mixture-until reaction begins and then controlling the reaction temperaturewithin the range of50* C: to 150 C. un-

til the reaction is'complete. Sincethe' reaction is exothermic, the completion of'the reaction is evidenced by the cessation'of heat liberation.

After the reaction is complete, the mixture is preferably cooled 'to' room temperature 'and 'the basic catalyst neutralized. Then succinonitrile is recovered 'from the reaction'mixture in any desire'dimanner. In the-"preferredfme'thod the'reaction mixture is distilled, employing "reduced pressurewhere-necessary to reduce'decomp'osition andcharring," to separate and recover the'various components of the. mixture. 'In'this mannensuccinonitrilein' excellent yield and in aLhigh' :degree of purityisobtained.

' Thefollowing :specific examples are ."given to illustrate thedetailedpractlce of :this invention as welb as to illustrate'zthe various'modiflca'tions which are within its scope. In all of the examples the parts are parts by weight.

Example I To a reactor equippedwith a mechanical stirrer, a reflux condenser, a thermometer and a means for heating and. cooling its contents, there was added '53 parts 'ofacrylonitrilef85 parts of acetone cyanohydrin, and I'A'parts of sodium hydroxide (1.0% by weight based on the totalreactants) dissolvedin lxlparts of water. The mixture was stirred and slowly heated to-'65 C. where'spontaneous refiuxbegan. Although heating of the reactants wasstopped, the reaction temperature ros'e'zto 78 CQiILZFJT'IIliTllltGS during .whichtime it wasrnecessary toicool tlie-reactants intermittently to'maintain andcontrolthe refluxrate. "Theoriginalcolorless mixture gradually-:fchanged -to :a dark-red-brownduring the reaction. As thereaction decreased in intensity heat was again applied to. maintainea reaction temperature of about 75 C. to .80'..C.. f or. an.-additional -.25 minutes .ater which time the temperat re .of .-thegreaction mixture Fraction Boiling Point Parts 1 C. to 63 C. at atmos. pressure 50. 6 2 63 0.150 137 0.211212 mm. Hg (i. 1 3 C. to C. at .0 mm. Hg 68.1 4 Black Resin Residue 16.7

Fractionl was identified as containing predominantlyacetone. Fraction 3 was a nearly colorless waxy cake' representing an 85% yield of succino- I nitrile with a clear point of 53 C. (the clear point r being-t'ha'ttemperature at which a small sample 'oftlie material became completely clear when slowly'ilieated in a small test tube).

The clear point remained unchanged when a portion of fraction- 3 was mixed with -a portion of, pure succinon-itrile having a-cleanpointof 57 C. A sample of fraction 3 was hydrolyzed toyield a'material having a melting point of 1 186 C. to l87 C.,- the melting point of succinic acid. 'Consequently,'-th e materialcalled fraction 3 wassuccinonitfile. a

The clear point-described above wasflemploycgl as a means fordetermining the purity ot-succi'noiv nitr ile prepared by l III-E process. Redistilld authentiosuccinonitrilc was found to have a clear point of 57 10. .Known quantities I of, acetone cyanohydrin were added toltheredisti'll'ed materiaLand the depression of the clear point was determined. .-The following tablev gives-the results of these findings.

Table I Percent by sight of fi f g 3g3; Centigrade By usin'g'the above tabulatedclear points apparent that the succinonitrile prepared in E-xample I'with a clear point of 53 C. contained little impurities, no'more than 2%.. The succinonitrile prepared in Example's'll to XII hereinbelow was also of high purity, as will be apparent.

- I "EXAMPLES II 'TO X11 InExamplesII .the-meth'od as' used in' ExamplezI was employed with the footnot'edfiexzceptions showninTable II. The reactants;-a'cry-v lonitri-le and 'ketone cyanohydrin; were employed in equimolecular proportions as in Example The 'per-tinent. reaction data 'as well-as the results ofthese examples .are tabulated below in Table;

Table II ACRYLONITRILE REACTED WITH KETONE CYANOHYDRIN Reaction Succinonitrile Example Cyanohydrin of Catalyst, per cent by weight, based on Numbe Ketone total reactants Time Tem Per 016 Min o i Poi t Yleld C'. II Acetone Triethylaminc, 2% 42 67-78 74 56 do NaOH, 157 v 48 6575 85 53 do T1;methylbenzylammonium-hydroxide, 29 67-75 86 50 do 34 51-75 83 53 do 47 63-76 85 53 do 92 65-74 17 49 Methyl Ethyl Ke- 55 65-92 78 57 tone. 1 IX o 35 64-91 83 54 X Methyl n-Hexyl Ke- 61 68-105 88 49 one. XI Methyl Isopropyl NaOH, 1% 42 71-93 88 52 Ketone. XII Cyclohexanone NaCN, 2% 107 73-95 95 45 2 Heat applied during entire reaction.

As illustrated by Examples II and VIII, when a volatile basic catalyst is employed in the process, it is not necessary to neutralize the base before distillation to recover the succinonitrile.

I The volatile base can be removed with one of the low boil fractions and re-used. When a nonvolatile base is employed as catalyst, however, it is preferably neutralized since the presence of basic material during the later stages of distillation may tend to cause resinification of succinonitrile with a needless increase in loss of the desired product.

Having described my invention by means of specific examples, I do not thereby desire or in tend to limit myself solely thereto, for as hereinbefore stated the proportions of reactants and reaction conditions employed may be varied and equivalent chemical compounds may be employed as set forth herein without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. The method of preparing succinonitril which comprises reacting acrylonitrile with a ketone cyanohydrin selected from the class consisting of aliphatic and alicyclic ketone cyanohydrins in the presence of a basic catalyst at a temperature from 50 C. to 150 C. and recovering the succinonitrile thus formed.

2. The method of preparing succinonitrile which comprises reacting acrylonitrile with acetone cyanohydrin in the presence of a basic catalyst at a temperature from 50 C. to 120 C. and recovering the succinonitrile thus formed.

3. The method of preparing succinonitrile which comprises reacting acryonitrile with acetone cyanohydrin at a temperature from 50 C. to 120 C. in the presence of 0.5% to by weight based on the total reactants of a basic material as a catalyst and recovering the succinonitrile thus formed. 7

4. The method of preparing succinonitrile which comprises preparing a reaction mixture containing acrylonitrile, a ketone cyanohydrin selected from the class consisting of aliphatic and alicyclic ketone cyanohydrins, and a basic catalyst, maintaining the said mixture at a temperature of 50 to C. whereupon chemical reaction occurs to form succinonitrile and a ketone corresponding to the original ketone cyanohydrin, and finally fractionally distilling the mixture to separate and recover the succinonitrile and the said ketone.

5. The method of claim 4 wherein the yanohydrin is acetone cyanohydrin and the basic catalyst is sodium hydroxide.

CHARLES E. BROCKWAY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Compds, (Reinhold), p. 174, 1947. 

1. THE METHOD OF PREPARING SUCCINONITRILE WHICH COMPRISES REACTING ACRYLONITRILE WITH A KETONE CYANOHYDRIN SELECTED FROM THE CLASS CONSISTING OF ALIPHATIC AND ALICYCLIC KETONE CYANOHYDRINS IN THE PRESENCE OF A BASIC CATALYST AT A TEMPERATURE FROM 50* C. TO 150* C. AND RECOVERING THE SUCCINONITRILE THUS FORMED. 